Companies usually have different groups of employees working different shifts/working hours a day.
For the setting to "enable off-in-lieu request", employees can claim off-in-lieu hours, which will be converted to days for leave application. However, not all employees have the same working hours a day. Therefore, I would suggest to have an option to assign the daily hours of work to each employee/department.
Companies which have employees working on shift, or having flexible working arrangement (eg. longer days, less days of work) will benefit from this.